A heavy smoke hanging over Hamilton County on Friday is from controlled burns in area forests, Bob Colby, executive director of the Air Pollution Control Bureau, said.
Mr. Colby said, though the fires "are filling us up with smoke, our monitoring today shows that we are well within the healthy range on particulate matters."
He said he received a call from state forestry officials on Thursday advising there would be controlled burns in Marion and Sequatchie counties.
The periodic burns are to prevent too much fuel build-up on the forest floor that would bring a much bigger fire if started by lightning or other sources, he said.
Mr. Colby said the wind was blowing from the east today so that some controlled fires in the Cherokee National Forest might be adding to the local smoke. A fire in Catoosa County was causing some of the heavy smoke.
Now is the ideal time for such controlled burns "before it greens up," he said.
Mr. Colby said he had noticed the heavy smoke while outside the office.